The present invention comprises a new and distinct cultivar of calla lily, botanically known as Zantedeschia sprengeri and hereinafter referred to by the cultivar name ‘Sumatra’.
‘Sumatra’ is a product of a planned breeding program, which had the objective of creating Zantedeschia hybrids for pot flower production in a wide range of colors with a large, classic flower shape. The breeding program began in 1989, and the new cultivar is a seedling selected from the crossing of Zantedeschia sprengeri ‘Black Star’ (female parent, U.S. Plant Pat. No. 14,844) with a Zantedeschia sprengeri selection referred to as C03002 (male parent, unpatented). ‘Sumatra’ was selected in 2006 by the inventor in 't Zand, The Netherlands as one flowering plant within the progeny of the stated cross.
The first act of asexual reproduction of ‘Sumatra’ by tissue culture was performed by the inventor in September of 2006 in 't Zand, The Netherlands. Subsequent asexual reproductions by tissue culture at the same location have demonstrated that the combination of characteristics as herein disclosed for the new cultivar are retained and reproduced true to type through successive generations of asexual reproduction.
The following observations, measurements and comparisons describe plants grown in a 14 cm pot at 12-14 weeks after planting in 't Zand, The Netherlands under greenhouse conditions, which approximate those generally used in horticultural practice. Color references are made to The 2001 R.H.S. Colour Chart of The Royal Horticultural Society of London, except where general color terms of ordinary significance are used.
The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.
The following traits have been repeatedly observed and determined to be basic characteristics of ‘Sumatra’ which, in combination, distinguish this calla lily as a new and distinct cultivar:                1. Purple-colored spathe;        2. Compact growth habit; and        3. High inflorescence production.        
Further, when compared to calla lily plant named ‘Samur’ (unpatented), the upper surface spathe color of ‘Samur’ varies between Red-Purple Group RHS 68B and 68C, whereas the upper surface spathe color of ‘Sumatra’ varies between Red-Purple Group RHS 59A and 59B. When compared to calla lily plant named ‘Accent’ (pending U.S. Plant patent application Ser. No. 14/544,476), ‘Accent’ demonstrates more numerous maculations on its upper and lower leaf surfaces than ‘Sumatra’. Additionally, the leaf margin color of ‘Accent’ varies between Green Group RHS 137A and 137D, while the leaf margin color of ‘Sumatra’ varies between Greyed-Purple Group RHS 187A to 187B.
Table 1 provides similarities and differences of ‘Sumatra’ to its parents, Zantedeschia sprengeri ‘Black Star’ and selection C03002.
TABLE 1‘Sumatra’SimilaritiesDifferences‘Black Star’Spathe shapeSpathe color (Both upper and lower surfacesvary between Greyed-Purple Group RHS187A to Black Group RHS 202A)Plant height (50-65 cm)C03002Leaf shapeNumber of inflorescences (3-10)Plant heightSpathe color (Pink—RHS value unknown)